1. Field of the Invention
The present invention relates to an edge inspection apparatus for inspecting an edge of a flat substrate such as a semiconductor wafer or a liquid crystal glass substrate.
2. Description of Related Art
The degree of integration of circuit patterns formed on a semiconductor wafer has recently been increasing year by year. The number of types of materials used in surface processing of wafers in production processing is also increasing in accompaniment with this. A boundary of a film created as a result of surface processing exists in the vicinity of an edge of a wafer. Observation of the vicinity of the edge of the wafer is therefore important in production processing. Management of defects in the vicinity of the surface of the edge influences the yield for circuits obtained from the wafer.
Because of this, in the related art, the vicinity of the edge of a flat substrate such as, for example, a semiconductor wafer is observed from a plurality of directions and the presence or absence of foreign matter, peeling of the film, bubbles within the film, wrapping around of the film, and cutting notches is inspected for.
Apparatus that detect foreign matter using light scattered as a result of illumination with laser light etc. exist as inspection apparatus for carrying out this inspection (refer to patent document 1).
(Patent Document 1) Japanese Laid-open Patent Publication No. H11-351850.
For example, when the edge of the semiconductor wafer is inclined with respect to a surface of the semiconductor, it is difficult for inspection apparatus of the related art to inspect conditions of this inclined surface.
It is therefore an object of the present invention to provide edge inspection apparatus capable of accurately inspecting conditions of an edge of a flat subject.